Hi. I'm the upstream of Padme, a mostly transparent proxy library for Python. I was adding support for the new matmul/@ operator when I noticed that MagicMock doens't support it yet.
>>> form unittest.mock import MagicMock
>>> MagicMock() @ 1
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: unsupported operand type(s) for @: 'MagicMock' and 'int'
To add support simply add 'matmul' to unittest.mock.numerics.